Steering control method and system of self-driving vehicle

ABSTRACT

The present disclosure provides for a steering control method and a steering control system for self-driving of a vehicle. The method comprises the steps of: obtaining information about an expected steering angle of a vehicle based on an automatic planning control operation; detecting whether an effective torque is applied to a steering wheel by a driver; and when it is detected that the driver has applied the effective torque to the steering wheel, computing a difference between a turning angle of the steering wheel controlled by the driver and the expected steering angle of a vehicle, and determining a self-driving intent prompt torque according to the difference between the two, wherein the self-driving intent prompt torque is to be applied to a steering system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/314,637, filed Dec. 31, 2018, which is a national phase applicationof International Application No. PCT/CN2016/088559, filed Jul. 5, 2016,each of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of vehicle control, inparticular to a steering control method and a steering control systemfor self-driving of a vehicle.

BACKGROUND

The development of vehicle technologies has facilitated productions andimplementation of self-driving vehicles.

In an existing steering control system of a self-driving vehicle, aplanning control system in the self-driving system computes a desiredturning radius of the vehicle based on a sensing positioning result, anda steering wheel is rotated to a determined position under turning anglecontrol.

Existing electric power steering (EPS) systems of vehicles may apply asteering assistance torque according to a driver's operations on thesteering wheel to help the driver to turn the steering wheel with asmall torque.

SUMMARY OF THE INVENTION

The inventors analyzed steering control systems of existing self-drivingvehicles and concluded that ultimately the steering control systems aimto control the steering wheel to reach an expected turning angle nomatter torque control or turning angle control is used. As a result,when the driver wants to intervene in the driving process, he mustconflict with the self-driving system and grab the control on thesteering wheel from the manipulator, which is not an ideal way to switchbetween manual driving and self-driving. As such, the existingself-driving systems can only work independently and cannot work inharmony with a human driver. This is because, in the conventionaltechnology, when the expected turning angle of the self-driving systemconflicts with the expected turning angle of the human driver, theself-driving system tries to cause the steering wheel to reach theexpected turning angle (which means a deviation from the operation ofthe human driver), or exits the self-driving state (which means manualintervention to regain the control on the vehicle).

However, an existing EPS system of a vehicle can assist the driver onlyby means of the driver's input and cannot implement an activeself-driving function.

The objective of the present invention is to overcome the disadvantagesand shortcomings in the prior art, and to propose a new steering controlmethod and a steering control system for self-driving of a vehicle sothat the driver and the self-driving system jointly participate in thedriving process.

According to an aspect of the present invention, a steering controlmethod for self-driving of a vehicle is provided, specificallyincluding:

firstly, a step for computing an expected vehicle steering angle,comprising obtaining information about an expected steering angle of avehicle based on an automatic planning control operation;

secondly, a step for detecting a driver's steering wheel operation,comprising detecting whether an effective torque is applied to asteering wheel by a driver; and

thirdly, a step for determining a self-driving intent prompt torque,comprising: when it is detected that the driver has applied theeffective torque to the steering wheel, computing a difference between aturning angle of the steering wheel controlled by the driver and theexpected steering angle of the vehicle, and determining a self-drivingintent prompt torque according to the difference, wherein theself-driving intent prompt torque is to be applied to a steering system.

Further, the step of determining a self-driving intent prompt torqueaccording to the difference may specifically include:

determining a larger self-driving intent prompt torque when thedifference between the turning angle of the steering wheel controlled bythe driver and the expected steering angle of the vehicle is larger,wherein the self-driving intent prompt torque is opposite to a torquethat the driver needs to provide. Hence, if the difference is larger,the torque that the driver needs to provide is larger.

Further, when the driver has applied the effective torque to thesteering wheel, the steering torque applied to the steering wheel mayinclude a steering torque applied by the driver, a steering assistancetorque of a vehicle steering assistance system, and the self-drivingintent prompt torque.

Further, the self-driving intent prompt torque τ_(c) may be determinedbased on the following formula:

τ_(c)=−sig (τ_(driver))·ƒ(ƒ abs(Δβ)), wherein Δβ may be determined basedon the following formula:Δβ=β_(e)−β_(driver)

wherein τ_(driver) denotes a torque currently applied by the driver,β_(e) denotes an expected turning angle of self-driving, β_(driver)denotes a turning angle where the steering wheel is located, and sig(τ_(driver)) denotes the direction of the torque currently applied bythe driver;

ƒ is a positive correlation function of an absolute value of Δβ and maysatisfy the following conditions:

$\left\{ {\begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix}\quad} \right.$

wherein τ_(eps) denotes a steering assistance torque.

Moreover, the method may further include a step of determining areliability status of operations of the self-driving system,specifically including:

in response to determining that an operating status of the self-drivingintent prompt torque is a high-reliability status, increasing theself-driving intent prompt torque determined according to the differencebetween the two and outputted by a steering controller in theself-driving intent prompt torque determination step; or

in response to determining that the operating status of the self-drivingsystem is a low-reliability status, decreasing the self-driving intentprompt torque determined according to the difference between the two andoutputted by the steering controller in the self-driving intent prompttorque determination step.

Further, the method for determining the reliability status of theoperations of the self-driving system may be based on a complexity of acurrent self-driving road environment and a severity of a lightingcondition.

Further, in the driver's steering wheel operation detecting step, whenit is detected that the driver has not applied the effective torque tothe steering wheel, the steering controller may control the turningangle of the steering wheel to reach the expected turning angle of theself-driving system.

According to another aspect of the present invention, a steering controlsystem of a vehicle is provided, the system including:

an expected vehicle steering angle computation unit for obtaininginformation about an expected steering angle of a vehicle based on anautomatic planning control operation;

a driver's operation detection unit for detecting whether an effectivetorque is applied to a steering wheel by a driver; and

a self-driving intent prompt torque determination unit for, when it isdetected that the driver has applied the effective torque to thesteering wheel, computing a difference between a turning angle of thesteering wheel controlled by the driver and the expected steering angleof the vehicle, and determining a self-driving intent prompt torqueaccording to the difference, wherein the self-driving intent prompttorque is to be applied to a steering system.

Further, the self-driving intent prompt torque determined by theself-driving intent prompt torque determination unit may include:

a larger self-driving intent prompt torque determined when thedifference is larger, wherein the self-driving intent prompt torque isopposite to a torque that the driver needs to provide, and thus if thedifference is larger, the torque that the driver needs to provide islarger.

Further, when the driver has applied the effective torque to thesteering wheel, the steering torque applied to the steering wheelincludes a steering torque applied by the driver, a steering assistancetorque of a vehicle steering assistance system and the self-drivingintent prompt torque.

Further, the self-driving intent prompt torque determination unit maydetermine the self-driving intent prompt torque τ_(c) based on thefollowing formula:τ_(c)=−sig(τ_(driver))·ƒ(ƒ abs(Δβ))

wherein Δβ may be determined based on the following formula:Δβ=β_(e)−β_(driver)

wherein τ_(driver) denotes a torque currently applied by the driver,β_(e) denotes an expected turning angle of self-driving, β_(driver)denotes a turning angle where the steering wheel is located, and sig(τ_(driver)) denotes the direction of the torque currently applied bythe driver;

ƒ is a positive correlation function of an absolute value of Δβ and maysatisfy the following conditions:

$\left\{ {\begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix}\quad} \right.$

wherein τ_(eps) denotes a steering assistance torque.

Furthermore, the steering control system may further include aself-driving system operating status determination unit for determininga reliability status of operations of the self-driving system, wherein:

the self-driving intent prompt torque determination unit increases theself-driving intent prompt torque determined according to the differenceand outputted by a steering controller in response to determining thatan operating status of the self-driving system is a high-reliabilitystatus; or

the self-driving intent prompt torque determination unit decreases theself-driving intent prompt torque determined according to the differenceand outputted by the steering controller when the operation of theself-driving system is determined to be in a low-reliability status.

Further, the method for determining the reliability status of theoperations of the self-driving system may be based on a complexity of acurrent self-driving road environment and a severity of a lightingcondition.

Moreover, the steering control system may further include an automaticsteering control unit for controlling the turning angle of the steeringwheel to reach the expected turning angle of the self-driving systemwhen the driver's operation detection unit detects that the driver hasnot applied the effective torque to the steering wheel.

Compared with the conventional EPS systems, the steering control methodand control system for self-driving of a vehicle according to theembodiments of the present invention can inspect whether a driver'soperations are consistent with self-driving expectations g according tocomputation results of the self-driving system, and determine aself-driving intent prompt torque to be applied according to a degree ofinconsistency. As such, the steering control method and control systemdisclosed herein can prompt the driver of the steering intent of theself-driving system, instead of passively assisting the driver'soperation only according to the driver's operations as in the EPSsystems. Also, compared with the existing self-driving steering controlsystems, they can affect the torque to be applied by the driver throughthe change of the self-driving intent prompt torque, thereby promptingthe human driver of the steering intent of the self-driving system,while ensuring the coexistence of the human driver and the self-drivingto avoid conflicts or exit of the self-driving state due to thedifference between the driver's steering intent and the self-drivingsteering intent in the past.

The steering control method and the steering control system according tothe present invention may affect a human driving operation by changingthe torque mode according to the expected steering angle computed by theself-driving system. The driver will not be forced to change his/hersteering operations but can be prompted with a recommended drivingbehavior from the self-driving, and in most cases, the driver canparticipate in the process of steering control with nearly no operation,thereby improving the safety and comfort of a driving experience.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present invention willbecome clearer and be understood more easily from the following detaileddescription of the embodiments of the present invention in combinationwith the accompanying drawings, in which:

FIG. 1 is a flow chart of a steering control method for self-driving ofa vehicle according to an embodiment of the present invention;

FIG. 2 is a structure diagram of a steering control system forself-driving of a vehicle according to an embodiment of the presentinvention;

FIG. 3 is a schematic structure diagram of a steering control system 300including an automatic steering control unit according to an embodimentof the present invention; and

FIG. 4 is an overview flow chart of a steering control method forself-driving of a vehicle according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

In order that those skilled in the art better understand the presentinvention, the present invention will be further described in detailbelow in combination with the accompanying drawings and specificembodiments.

FIG. 1 is a schematic block diagram of a steering control system 100 forself-driving of a vehicle according to an embodiment of the presentinvention.

The steering control system 100 may include the following units: adriver's operation detection unit 110, an expected vehicle steeringangle computation unit 120, and a self-driving intent prompt torquedetermination unit 130.

Optionally, the steering control system 100 may further include asteering torque application unit 140.

The driver's operation detection unit 110 may be configured to detectwhether an effective torque is applied to a steering wheel by a driver.

Generally, a torque sensor is provided on the steering wheel. When thedriver turns the steering wheel, the torque sensor may detect a torqueinput. At this time, it is determined that the driver is operating thesteering wheel, that is, an effective torque is applied to the steeringwheel. If the torque sensor does not detect a torque input, it may bedetermined that the driver does not operate the steering wheel, that is,no effective torque is applied to the steering wheel.

The expected vehicle steering angle computation unit 120 may beconfigured to obtain information about an expected steering angle of avehicle based on an automatic planning control operation.

For example, the expected steering angle of the vehicle may be obtainedbased on a planning control operation carried out according to a sensingand positioning input.

The self-driving intent prompt torque determination unit 130 may beconfigured to compute a difference between a turning angle of thesteering wheel controlled by the driver and the expected steering angleof a vehicle and determine a self-driving intent prompt torque accordingto the difference, when it is detected that the driver has applied theeffective torque to the steering wheel, wherein the self-driving intentprompt torque is to be applied to a steering system.

In one example, when the self-driving intent prompt torque determinationunit 130 determines a larger self-driving intent prompt torque when thedifference between the turning angle of the steering wheel controlled bythe driver and the expected steering angle of the vehicle is larger whendetermining a self-driving intent prompt torque, wherein theself-driving intent prompt torque is opposite to a torque that thedriver needs to provide, so that the torque that the driver needs toprovide is larger. Thus, when the driver operates the steering wheel, asthe steering wheel gradually approaches the expected steering angle ofthe vehicle, the driver may feel more and more labor-saving and can thusrealize that his driving process is consistent with the self-drivingcontrol intent. Otherwise, when the steering angle gradually deviatesfrom the expected steering angle, the driver may feel more and morelaborious and can thus realize that his driving process is contrary tothe self-driving control intent.

After the driver realizes the self-driving control intent, he candetermine whether he made a mistake in the previous operation. If heconfirms that he did not make a mistake, he can make adjustments intime. If he confirms that his operation has not been mistaken, he can,for example, ignore the self-driving control intent, continue to operateas originally planned or temporarily turn off the self-driving control(for example, via an option button for exiting the self-driving controlprovided by the vehicle), and concentrate on driving the vehicleaccording to the driver's own intent.

In the conventional EPS systems, the torque for driving the steering ofthe wheel is composed of a steering torque applied by the driver and asteering assistance torque of the steering assistance system.

According to the steering control system of the embodiment of thepresent invention, when it is detected that the driver has applied theeffective torque to the steering wheel, the self-driving system and thedriver jointly participate in the steering process by applying theself-driving intent prompt torque.

According to an embodiment of the present invention, when the driver hasapplied the effective torque to the steering wheel, the steering torqueapplied to the steering wheel by the steering torque application unit140 may include a steering torque applied by the driver, a steeringassistance torque of a vehicle EPS system and the self-driving intentprompt torque.

That is, the steering torque at this time may be determined based on thefollowing formula (1):τ=τ_(driver)+τ_(eps)+τ_(c)  (1)

wherein τ_(driver) is a driver's steering torque, τ_(eps) is an EPSsteering assistance torque, and τ_(c) is a self-driving intent prompttorque.

When the specified steering angle is zero, the torque may be zero, thecounterclockwise torque is positive, and the clockwise torque isnegative.

In one example, the self-driving intent prompt torque τ_(c) may bedetermined based on the following formula (2):τ_(c)=−sig(τ_(driver))·ƒ(ƒ abs(Δβ))  (2)

wherein Δβ is determined based on the following formula (3):Δβ=β_(e)−β_(driver)  (3)

wherein τ_(driver) denotes a torque currently applied by the driver,β_(e) denotes an expected turning angle of self-driving, β_(driver)denotes a turning angle where the steering wheel is located, and sig(τ_(driver)) denotes the direction of the torque currently applied bythe driver;

ƒ is a positive correlation function of an absolute value of Δβ and maysatisfy conditions (4):

$\begin{matrix}\left\{ \begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix} \right. & (4)\end{matrix}$

wherein cτ_(eps) denotes a steering assistance torque, and ƒ abs(τ_(c))denotes an absolute value of τ_(c).

According to the steering control system of the embodiment of thepresent invention, after the self-driving intent prompt torque isincreased, the system may make the driver feels that it is morelabor-saving to control the steering wheel to turn to the expectedsteering angle of the self-driving system, and that it is more laboriousto control the steering wheel to turn opposite to the expected steeringangle of the self-driving system.

In one example, the steering control system may adopt a self-drivingintent prompt torque strategy in consideration of an operating state ofthe self-driving system in addition to the difference between thedriver's operation and the expected turning angle of the self-drivingsystem, and may change the magnitude of the self-driving intent prompttorque according to the reliability of the self-driving state, therebychanging the degree of participation of the machine driving in thedriving process. The steering control system that determines theself-driving intent prompt torque in consideration of the operatingstate of the self-driving system will be described below in combinationwith FIG. 2.

FIG. 2 shows a structure diagram of a steering control system 200 thatdetermines a self-driving intent prompt torque in consideration of anoperating state of a self-driving system according to another embodimentof the present invention.

As shown in FIG. 2, compared with the steering control system 100 ofFIG. 1, the steering control system 200 further includes a self-drivingsystem operating state determination unit 250 besides the driver'soperation detection unit 210, the expected vehicle steering anglecomputation unit 220, the self-driving intent prompt torquedetermination unit 230 and the optional steering torque application unit240. The functions and working principles of the driver's operationdetection unit 210, the expected vehicle steering angle computation unit220 and the steering torque application unit 240 are similar to those ofthe corresponding units of FIG. 1, and are not redundantly describedherein. The driving system operating state determination unit 250 andthe self-driving intent prompt torque determination unit 230 will bemainly described below.

The self-driving system operating state determination unit 250 may beconfigured to determine a reliability status of operation of theself-driving system. For example, the self-driving system operatingstate determination unit 250 may determine a reliability status ofoperation of the self-driving system in combination with the surroundingenvironment (geography, weather, lighting, etc.) where the vehicle islocated and/or feedback given by the driver, etc.

For example, if the self-driving system detects that the currentenvironment is complex or the lighting condition is bad, theself-driving system operating state determination unit 250 may determinethat there may be a high probability that the self-driving system is ina low-reliability operating state. Alternatively, if the self-drivingsystem detects that the current environment is simple and the lightingcondition is good, the self-driving system operating state determinationunit 250 may determine that the self-driving system is in ahigh-reliability operating state.

When the self-driving system operating state determination unit 250determines that there is a high probability that the self-driving systemis in a low-reliability operating state, the self-driving intent prompttorque determination unit 230 may reduce (lower) the amplitude of theself-driving intent prompt torque, and the system at this time may besimilar to the conventional EPS systems. Alternatively, when theself-driving system operating state determination unit 250 determinesthat there is a high probability that the self-driving system is in ahigh-reliability operating state, the self-driving intent prompt torquedetermination unit 230 may increase the magnitude of the self-drivingintent prompt torque to provide an obvious enhanced driving experiencefor the driver's steering operations.

As an example, the steering control system for self-driving of thevehicle according to an embodiment of the present invention may furtherinclude an automatic steering control unit for, when the driver'soperation detection unit does not detect that the driver has operatedthe steering wheel, i.e., the driver has not applied the effectivetorque to the steering wheel, controlling the turning angle of thesteering wheel to reach the expected turning angle of the self-drivingsystem, and the automatic steering control unit at this time isconsistent with the conventional self-driving steering control system infunction.

FIG. 3 is a block diagram schematically showing a steering controlsystem 300 including an automatic steering control unit according to anembodiment of the present invention.

Compared with the steering control system 200 of FIG. 2, the steeringcontrol system 300 of FIG. 3 may further include an automatic steeringcontrol unit 360. The automatic steering control unit 360 may receivethe monitoring result of the driver's operation detection unit 310, andcontrols the steering torque application unit 340 to apply a torquecorresponding to the turning angle determined by the self-driving systemin the expected direction of the vehicle to the steering wheel when thedriver's operation detection unit 310 does not detect that the driverhas operated the steering wheel, i.e., the driver has not applied theeffective torque to the steering wheel, so that the steering wheel mayreach the expected turning angle of the self-driving system. The torqueapplied by the steering torque application unit 340 at this time doesnot include the aforementioned torque applied by the driver, the EPSassist torque and the self-driving intent prompt torque.

A steering control method in accordance with the above-describedsteering control system according to an embodiment of the presentinvention will be described below in combination with FIG. 4.

FIG. 4 is a generic flow chart of a steering control method forself-driving of a vehicle according to an embodiment of the presentinvention.

As shown in FIG. 4, an embodiment of the present invention provides asteering control method for self-driving of a vehicle, including stepsS410 to S430.

In step S410, information about an expected steering angle of a vehiclemay be obtained based on an automatic planning control operation.

In step S420, whether an effective torque has applied to a steeringwheel by a driver is detected.

In step S430, when it is detected that the driver has applied theeffective torque to the steering wheel, a difference between a turningangle of the steering wheel controlled by the driver and the expectedsteering angle of the vehicle is computed, and a self-driving intentprompt torque is determined according to the difference between the twoand applied to a steering system.

According to the steering control method of the embodiment of thepresent invention, when it is detected that the driver has applied theeffective torque to the steering wheel, the self-driving system and thedriver jointly participate in the steering process by applying theself-driving intent prompt torque.

In one example, in step S430, when the self-driving intent prompt torqueis determined according to the difference between the turning angle ofthe steering wheel controlled by the driver and the expected steeringangle of the vehicle, and the difference between the turning angle ofthe steering wheel controlled by the driver and the expected steeringangle of the vehicle is larger, a larger self-driving intent prompttorque is determined, and the self-driving intent prompt torque isopposite to a torque that the driver needs to provide, so that thetorque that the driver needs to provide is larger.

Specifically, the steering torque applied to the steering wheel mayinclude a steering torque applied by the driver, a steering assistancetorque of a vehicle steering assistance system and the self-drivingintent prompt torque. That is, the steering torque T at this moment maybe determined based on the following formula:τ=τ_(driver)+τ_(eps)+τ_(c),

wherein τ_(driver) is a driver's steering torque, τ_(eps) is a steeringassistance torque, and τ_(c) is a self-driving intent prompt torque.When the specified steering angle is zero, the torque is zero, thecounterclockwise torque is positive, and the clockwise torque isnegative. The computational formula of the compensation torque, that is,the self-driving intent prompt torque τ_(c), is determined based on thefollowing formula:τ_(c)=−sig(τ_(driver))·ƒ(ƒ abs(Δβ))

wherein Δβ is determined based on the following formula:Δβ=β_(e)−β_(driver)

wherein τ_(driver) denotes a torque currently applied by the driver,β_(e) denotes an expected turning angle of self-driving, β_(driver)denotes a turning angle where the steering wheel is located, and sig(τ_(driver)) denotes the direction of the torque currently applied bythe driver;

ƒ is a positive correlation function of an absolute value of Δβ and maysatisfy the following condition:

$\left\{ {\begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix}\quad} \right.$

wherein τ_(eps) denotes a steering assistance torque, and ƒ abs(τ_(c))denotes an absolute value of τ_(c). It should be noted that the steeringtorque τ required for steering at a certain moment is definite, and isdetermined by a resistance torque fed back by the ground. Theself-driving intent prompt torque is opposite to the driver's torque.Thus, when the self-driving intent prompt torque is large (thedifference between the steering angle and the expected turning angle ofthe vehicle is large), a larger driver torque is required to obtain therequired steering torque τ; as the steering angle changes, thedifference between the steering angle and the expected turning angle ofthe vehicle changes, then the self-driving intent prompt torque changes,and the torque that the driver needs to provide also changes, therebyachieving the purpose of providing a self-driving intent to the driver.

It can be clearly seen from the above formula and analysis that,according to the steering control method of the embodiment of thepresent invention, after the self-driving intent prompt torque isincreased, the driver may feel that it is more labor-saving to controlthe steering wheel to turn to the expected steering angle of theself-driving system, and it is more laborious to control the steeringwheel to turn opposite to the expected steering angle of theself-driving system.

For example, it is assumed that according to the current steering angle,the total steering torque is 4 Nm (Newton meters), wherein the steeringassistance torque is 3 Nm, and that when the self-driving system is notstarted, the driver provides an additional torque of 1 Nm. After theself-driving system is started, if the difference Δβ between theexpected turning angle of the self-driving system and the driver'sturning angle is 5 degrees, the self-driving intent prompt torque τ_(c)is −1 Nm, then the torque that the driver needs to provide is 2 Nm. Whenthe difference Δβ between the expected turning angle of the self-drivingsystem and the driver's turning angle is increased to 10 degrees, theself-driving intent prompt torque τ_(c) is −3 Nm, then the torque thatthe driver needs to provide becomes 4 Nm. As a result, the driver needsto provide a larger steering torque for maintaining the current turningangle. Hence, when the difference Δβ between the expected turning angleof the self-driving system and the driver's turning angle is large, thedriver feels laborious, thereby being able to realize the inconsistencybetween his current operation and the expectation of the self-drivingsystem.

According to the steering control method of the embodiment of thepresent invention, in one example, the self-driving intent prompt torquedetermination strategy may also consider the operating state of theself-driving system besides the difference between the driver'soperation and the expected turning angle of the self-driving system.

For example, a reliability status of operations of the self-drivingsystem can be determined according to the complexity of the currentself-driving road environment and the severity of the lightingcondition. For example, if the self-driving system detects that thecurrent environment is complex or the lighting condition is bad, it maybe in a low-reliability operating state. In such a case, the amplitudeof the self-driving intent prompt torque may be reduced and the systemmay be similar to the conventional EPS systems. Alternatively, if theself-driving system detects that the current environment is simple andthe lighting condition is good, it is in a high-reliability operatingstate, and the amplitude of the self-driving intent prompt torque isincreased to provide an obviously enhanced driving feel for the driver'ssteering operation.

In the steering control method of the present embodiment, when it is notdetected that the driver has operated the steering wheel, i.e., thedriver has not applied the effective torque to the steering wheel, theself-driving system controls the turning angle of the steering wheel toreach the expected turning angle of the self-driving system, and theself-driving system at this time is consistent with the conventionalself-driving steering control system in function.

Compared with the conventional EPS systems, the steering control methodand control system for self-driving of a vehicle according to theembodiments of the present invention can inspect whether the driver'soperation is consistent with the self-driving expectation according tothe computing result of the self-driving system, and determine aself-driving intent prompt torque to be applied according to the degreeof inconsistency, thereby being able to prompt the driver of thesteering intent of the self-driving system, instead of passivelyassisting the driver's operation only according to the driver'soperation as in the EPS system; and compared with the existingself-driving steering control system, they can affect the torque to beapplied by the driver through the change of the self-driving intentprompt torque, thereby prompting the human driver of the steering intentof the self-driving system, but ensuring the coexistence of the humandriver and the self-driving to avoid the conflict or exit of theself-driving state due to the difference between the driver's steeringintent and the self-driving steering intent in the past.

The steering control method and the steering control system according tothe present invention affect a human driving operation by changing thetorque mode according to the expected steering angle computed by theself-driving system. The driver will not be forced to change his/hersteering operation but can be prompted with a recommended drivingbehavior from the self-driving, and in most cases, the driver canparticipate in the process of steering control with nearly zerooperation, thereby improving the safety and comfort of a drivingprocess.

It should be noted that the vehicle in the description should beunderstood in a broad sense, including various large, medium and smallvehicles, water vehicles, trans-atmospheric vehicles, etc.

It should be noted that relevant steps of the method may be performedlocally in the vehicle, or in the cloud, or both locally and in thecloud.

It should be noted that although the steps in the flow chart are shownin a certain order, this does not mean that the steps can only beperformed in this order, but as long as there is no logicalinterdependence between the steps, the steps may be performed in areverse order or in parallel.

The above-described embodiments of the present invention are exemplarybut not exhaustive and are not limited to the disclosure. Manymodifications and alterations will be apparent to those of ordinaryskill in the art without departing from the scope and spirit of theembodiments described. Therefore, the scope of the present inventionshall be subjected to the scope of the claims.

The invention claimed is:
 1. A method for self-driving a vehicle,comprising: obtaining information about an expected steering angle ofthe vehicle based on an automatic planning control operation; detectingwhether an effective torque is applied to a steering wheel by a driver;and determining a self-driving intent prompt torque, comprising: inresponse to detecting that the driver has applied the effective torqueto the steering wheel, computing a difference between a turning angle ofthe steering wheel controlled by the driver and the expected steeringangle of the vehicle; and determining a self-driving intent prompttorque based on a positive correlation function of a value of thedifference and a direction of a steering torque applied by the driver;and applying a steering torque to the steering wheel, wherein when thedriver has applied the effective torque to the steering wheel, thesteering torque applied to the steering wheel comprises a combination ofthe steering torque applied by the driver, a steering assistance torqueapplied by a vehicle steering assistance system, and the self-drivingintent prompt torque, and wherein the self-driving intent prompt torqueis opposite to the steering torque applied by the driver.
 2. The methodof claim 1, wherein determining the self-driving intent prompt torquebased on the positive correlation function of the value of thedifference and the direction of the steering torque applied by thedriver comprises: determining a larger self-driving intent prompt torquewhen the difference is larger, and wherein a torque that the driver isto provide is larger if the difference is larger.
 3. The method of claim1, wherein the self-driving intent prompt torque is determined based onthe following formula:τ_(c)=−sig(τ_(driver))·ƒ(ƒ abs(Δβ)) wherein τ_(c) is the self-drivingintent prompt torque, wherein Δβ is determined based on the followingformula:Δβ=β_(e)−β_(driver), wherein τ_(driver) denotes the steering torqueapplied by the driver, β_(e) denotes the expected steering angle of thevehicle, β_(driver) denotes the turning angle of the steering wheel, andsig(τ_(driver)) denotes the direction of the steering torque applied bythe driver; wherein ƒ is the positive correlation function of anabsolute value of Δβ and satisfies the following conditions:$\left\{ {\begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix},} \right.$ and wherein τ_(eps) denotes the steeringassistance torque, and ƒ abs(τ_(c)) denotes an absolute value of τ_(c).4. The method of claim 1, further comprising: determining a reliabilitystatus of operations of a self-driving system; and adjusting theself-driving intent prompt torque based on the reliability status ofoperations of the self-driving system.
 5. The method of claim 4, whereinthe method for determining the reliability status of operations of theself-driving system comprises: determining the reliability status ofoperations of the self-driving system based on a complexity of a currentself-driving road environment and a severity of a lighting condition. 6.The method of claim 1, further comprising: in response to detecting thatthe driver has not applied the effective torque to the steering wheel,controlling the turning angle of the steering wheel to reach theexpected steering angle of the vehicle.
 7. The method of claim 1,wherein the steering torque applied to the steering wheel is determinedbased on the following formula:τ=τ_(driver)+τ_(eps)+τ_(c), wherein τ denotes the steering toque appliedto the steering wheel, wherein τ_(driver) denotes the steering torqueapplied by the driver, wherein τ_(eps) denotes the steering assistancetorque applied by the vehicle steering assistance system, and whereinτ_(c) denotes the self-driving intent prompt torque.
 8. The method ofclaim 1, wherein detecting that the driver has applied the effectivetorque to the steering wheel comprises determining that the driver isoperating the steering wheel.
 9. A system for controlling a vehicle,comprising: an expected vehicle steering angle computation unitconfigured to obtain information about an expected steering angle of thevehicle based on an automatic planning control operation; a driveroperation detection unit configured to detect whether an effectivetorque has been applied to a steering wheel by a driver; and aself-driving intent prompt torque determination unit configured to:compute a difference between a turning angle of the steering wheelcontrolled by the driver and the expected steering angle of the vehiclein response to detecting that the driver has applied the effectivetorque to the steering wheel; and determine a self-driving intent prompttorque based on a positive correlation function of a value of thedifference and a direction of a steering torque applied by the driver;and a steering torque application unit configured to apply a steeringtorque to the steering wheel, wherein when the driver has applied theeffective torque to the steering wheel, the steering torque applied tothe steering wheel comprises a combination of the steering torqueapplied by the driver, a steering assistance torque applied by a vehiclesteering assistance system, and the self-driving intent prompt torque,and wherein the self-driving intent prompt torque is opposite to thesteering torque applied by the driver.
 10. The system of claim 9,wherein, to determine the self-driving intent prompt torque based on thepositive correlation function of the value the difference and thedirection of the steering torque applied by the driver, the driver'soperation detection unit is further to determine a larger self-drivingintent prompt torque when the difference is larger, and wherein a torquethat the driver is to provide is larger if the difference is larger. 11.The system of claim 9, wherein the self-driving intent prompt torquedetermination unit determines the self-driving intent prompt torquebased on the following formula:τ_(c)=−sig(τ_(driver))·ƒ(ƒ abs(Δβ)) wherein Δβ is determined based onthe following formula:Δβ=β_(e)−β_(driver) wherein τ_(driver) denotes the steering torqueapplied by the driver, β_(e) denotes the expected steering angle of thevehicle, β_(driver) denotes the turning angle of the steering wheel, andsig(τ_(driver)) denotes the direction of the steering torque applied bythe driver; wherein ƒ is the positive correlation function of anabsolute value of Δβ and satisfies the following conditions:$\left\{ {\begin{matrix}{{f(0)} = 0} \\{0 \leq {f\;{{abs}\left( \tau_{c} \right)}} \leq {{f{abs}}\left( \tau_{eps} \right)}}\end{matrix},} \right.$ and wherein τ_(eps) denotes the steeringassistance torque, and ƒ abs(τ_(c)) denotes an absolute value of τ_(c).12. The system of claim 9, a self-driving system operating statedetermination unit configured to: determine a reliability status ofoperations of a self-driving system; and adjust the self-driving intentprompt torque based on the reliability status of operations of theself-driving system.
 13. The system of claim 12, wherein theself-driving system operating state determination unit is furtherconfigured to: determine the reliability status of operations of theself-driving system based on a complexity of a current self-driving roadenvironment and a severity of a lighting condition.
 14. The system ofclaim 9, further comprising: an automatic steering control unitconfigured to control the turning angle of the steering wheel to reachthe expected steering angle of the vehicle in response to detecting thatthe driver has not applied the effective torque to the steering wheel.15. The system of claim 9, wherein the steering torque application unitis configured to determine the steering torque applied to the steeringwheel based on the following formula:τ=τ_(driver)+τ_(eps)+τ_(c), wherein τ denotes the steering toque appliedto the steering wheel, wherein τ_(driver) denotes the steering torqueapplied by the driver, wherein τ_(eps) denotes the steering assistancetorque applied by the vehicle steering assistance system, and whereinτ_(c) denotes the self-driving intent prompt torque.
 16. The system ofclaim 9, wherein, to detect that the driver has applied the effectivetorque to the steering wheel, the driver operation detection unit isfurther configured to detect that the driver is operating the steeringwheel.